1. Field
The embodiments described below relate generally to delivery of radiotherapy treatment. More specifically, some embodiments are directed to controlling dynamic and static axes during radiation treatment of moving targets and systems for delivering such treatments.
2. Description
Radiotherapy or radiation therapy is used to treat cancer and other diseases with ionizing radiation. Conventional radiotherapy systems generate and direct a beam of radiation to a targeted treatment volume within a patient. The radiation beam is intended to injure or destroy cells within the target volume by causing ionizations within the cells or other radiation-induced cell damage.
Radiotherapy treatment plans for delivering radiation to a patient are intended to maximize radiation delivered to a target area, while minimizing the radiation delivered to surrounding healthy tissue. In this regard, the treatment of a moving target area poses a challenge to radiotherapy, including the accuracy with which the target area will be radiated as compared to a static target area. In the context of radiotherapy treatments, the treatment of moving targets is further complicated due to the movement of the gantry and other components of the radiotherapy apparatus and/or the patient. Such radiotherapies include but are not limited to Arc-Modulated ConeBeam Therapy, Intensity Modulated Arc Therapy, and a variety of other radiotheraopy treatment schemes that involve rotating a linear accelerator (LINAC) gantry or other motorized axis about the patient and delivering radiation to a targeted patient area from a number of different gantry angles. In some contexts, the delivery of the treatment radiation may be either continuous or at discrete locations.
One conventional method for addressing the delivery of radiation treatment to moving targets includes using an increased margin of delivery around a target that is large enough to account for target excursions from a nominal position. While the increased margin may result in the target receiving a desired radiation dose, surrounding healthy tissue or organs are at an increased risk of also receiving radiation. Gated treatment techniques to address moving targets involve determining a gating window during which the target movement is minimized to deliver the radiation treatment. For example, radiation may be delivered to the target only when the patient is within 80% exhalation of the breathing cycle, a period when motion of the targeted treatment area may be relatively motionless. However, acquisition of planning images (e.g., 4D CT computed tomography) and a breathing monitoring device to provide an indication of the phases of the patient's breathing cycle are needed for this technique. One proposed technique for delivering radiation to a moving target involves using an auxiliary device to determine the location and the shape of the target at any point in time and reshaping a beam shaping device (e.g., a MLC or multileaf collimator leaves) of the radiotherapy system to follow (i.e., track) the target shape at any point in time. However, this technique also requires an auxiliary device in addition to the radiotherapy system.
The present inventor has realized that conventional radiation treatments are inefficient and insufficient for radiotherapy treatment involving moving aspects of a radiotherapy system and moving targets. Accordingly, other methods and systems to provide radiation treatment of moving components of a radiotherapy system and moving target areas are desired.